We've all been children, we all know a parent or parent-figure. This makes us all potential writers of children's books. I think of children's books as not so much for children, but as the filling that goes between the child world and the adult world. One way or another, all children's books have to negotiate that space, whether it's thinking about how the text of a picture book will sound when read aloud, or how the child views him or herself in a world run by adults. And before it reaches the hand, eye or ear of a child there are many adults to deal with: editors, illustrators, publicists, marketing people, the buying adults. And of course, more than likely, you're an adult reading this, so the moment you think about writing something for children, you'll be handling something or other from your own childhood. This may be something you read, experiences of being read to, pleasurable or painful experiences from when you were young.

There is also an interesting line between the child you once were and the children you know now. If you want to write a book for children, you will find yourself travelling to and fro along this line, wondering one moment about what kind of child you were, why you had those particular tastes and interests, what depressed or excited you, what you were afraid of, what you yearned for; the next, looking, listening and thinking about the children you know or meet. Are there big differences, or is there some core child-ness that is unchanged? Is the culture and background you came from, similar or different to the kinds of children you know and meet now? If so, how does your writing reach them?

So you know you want to write something. As you'll read in the rest of this booklet, children's literature has very specific forms or genres. It may sometimes seem to you that editors can only think inside specific boxes, whereas a book you liked, The Little Prince, say, defied such boxes. So you'll hear from editors, comments like: "There's no point in writing a picture book text that's longer than a couple of hundred words", "That story is too 'old' for a picture book audience", "Your story is too short" and so on. Bafflingly, if you go to the library and pick up a pile of books, you may well find some that seem to defy such boundaries. Nearly always, that's because it's a famous author who's been granted leeway to write what they want - Roald Dahl's The Minpins is an example of that. Or you've got in your hand a book produced by an independent company, a firm like Tamarind, Frances Lincoln or Barefoot Books.

What this means is that any of us who write for children have to do homework. We have to be very aware of both what is being published and how people are telling stories these days. The writer Morris Gleitzman told me that he sets himself one golden rule when he writes for children: "Start any scene as 'late' into the action or dialogue as you can." In other words, don't hang about. That's his perception of today's audience.

If you're serious about writing, you'll need some kind of axiom (or several) like that so that you put yourself in control of what you're putting down on the page.

We also have to spend time in bookshops, libraries, nurseries, schools and with reading children, seeing how the books work with the audiences. You are of course the first audience for what you write, but you want to make yourself the kind of reader who can pretend to be the reading child. You've got to build in a sense of your audience as part of the way in which you're tough with yourself about what you're writing. Part of that reading child will inevitably be the reading child you once were. That's no bad thing, but quite often, I would suggest, this is not sufficient. You also need to get that child who is now the age of your target audience into your head too.

The world of children's books is a very friendly, decent place to be. It's full of people who are desperate to enlighten, interest and excite children in ideas, imaginary worlds and contemporary issues. Everywhere you look in this world, you'll find very committed, low-paid people, who will go the extra mile if it means reaching a child who might not otherwise come across a book. There are a whole host of organisations trying to foster a love of reading and the moment you've got something written and published, no matter how modest, there are all sorts of places that will be interested in inviting you to share what your book with some children. A very important part of writing for children is appearing at book festivals, and in libraries and schools. An important part of becoming a writer for children is seeing what published writers do and say when they appear. Writing children's books may be as lonely as any other kind of writing, but there is a big social element in how the books are taken to the readers. There are thousands of people out there doing this - parents, librarians and teachers mostly - so part of being a writer for children is being among these people at the events they organise. If you get the balance right, this will be part of what motivates you to go back into the cell and write some more!

· Michael Rosen is the Children's Laureate. He has written 140 books of poetry and fiction for children